下颌持续前导对成年及幼年期大鼠髁突软骨血管内皮生长因子表达和Micro-CT下髁突骨质变化的差异
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摘要
背景:既往实验结果表明下颌前导能够使幼年期大鼠髁突发生改建,表现为促进髁突组织生长。但下颌前导对成年期大鼠髁突改建影响以及在髁突软骨超微结构等方面与幼年期大鼠的差异仍是研究的关键。目的:观察成年期大鼠与幼年期大鼠在下颌持续前导作用下髁突软骨的改建差异以及超微结构的变化。方法:30只4周龄的SD大鼠和30只9周龄的SD大鼠建立下颌前导模型。分别随机分为是实验组(15只)和对照组(15只)。实验组坚持佩戴上颌斜面导板,对照组不需要佩戴该装置,分别在第3,7,14,21,30天处死动物并取材,免疫组织化学染色检测血管内皮生长因子在髁突中的表达及分布,MicroCT分析髁突骨质的变化。结果与结论:(1)与对照组相比,实验组成年期大鼠与幼年期大鼠血管内皮生长因子阳性细胞率及灰度值在第7天开始增多,成年期大鼠实验组30 d时达到最高值(P <0.01);幼年期大鼠实验组21 d时达到最大值(P <0.01),30d时灰度值较21d时减小,但仍大于对照组;(2)与对照组相比,Micro-CT显示实验组的新生骨和骨小梁厚度、骨小梁数量和分离度随时间延长而增加;(3)在下颌持续前导下,成年期与幼年期大鼠髁突软骨出现增生性改建,并存在血管内皮生长因子的高表达,但是幼年期大鼠更易发生适应性改建。
BACKGROUND: Previous experimental results have shown that mandibular advancement can remodel the condylar process in growing rats, which is shown to promote the growth of condylar tissue. However, the influence of mandibular advancement on condylar remodeling and ultrastructure of condylar cartilage in adult rats different from those in growing rats are still a key issue. OBJECTIVE: To observe the condylar remodeling and ultrastructural variations in the mandibular condylar cartilage in adult and growing rats undergoing mandibular advancement. METHODS: Thirty 9-week-old male Sprague-Dawley rats and thirty 4-week-old male Sprague-Dawley rats were randomly divided into experimental and control groups with 15 adult rats and 15 growing rats in each group. Rats in the experimental group were subjected to wearing mandibular advancement splints. Rats were sacrificed on days 3, 7, 14, 21, and 30. Sections from the condyles were cut, and vascular endothelial growth factor expression in the condylar cartilage was examined through immunohistochemical analysis. These samples were also observed under Micro-CT. RESULTS AND CONCLUSION: Compared with the control group, the number of vascular endothelial growth factor positive cells in the condylar cartilage and the gray value gradually increased in the experimental group on day 7 of the intervention: for the adult rats, the positive cell number and gray value were at the maximum level on day 30(P < 0.01), while for the growing rats, the highest number of positive cells and gray value appeared on day 21(P < 0.01), and the gray value on day 30 was lower than that on day 21 but still higher than that in the control group. Micro-CT revealed that the trabecula and the newly formed bone in the experimental group gradually thickened, and the number and separation of trabeculae increased with time. To conclude, both adult and growing rats display hyperplastic remodeling in the condyle with the presence of high expression of vascular endothelial growth factor under continuous mandibular advancement. However, the adaptive remodeling is earlier in the growing rats than in the adult rats.
BACKGROUND: Previous experimental results have shown that mandibular advancement can remodel the condylar process in growing rats, which is shown to promote the growth of condylar tissue. However, the influence of mandibular advancement on condylar remodeling and ultrastructure of condylar cartilage in adult rats different from those in growing rats are still a key issue. OBJECTIVE: To observe the condylar remodeling and ultrastructural variations in the mandibular condylar cartilage in adult and growing rats undergoing mandibular advancement. METHODS: Thirty 9-week-old male Sprague-Dawley rats and thirty 4-week-old male Sprague-Dawley rats were randomly divided into experimental and control groups with 15 adult rats and 15 growing rats in each group. Rats in the experimental group were subjected to wearing mandibular advancement splints. Rats were sacrificed on days 3, 7, 14, 21, and 30. Sections from the condyles were cut, and vascular endothelial growth factor expression in the condylar cartilage was examined through immunohistochemical analysis. These samples were also observed under Micro-CT. RESULTS AND CONCLUSION: Compared with the control group, the number of vascular endothelial growth factor positive cells in the condylar cartilage and the gray value gradually increased in the experimental group on day 7 of the intervention: for the adult rats, the positive cell number and gray value were at the maximum level on day 30(P < 0.01), while for the growing rats, the highest number of positive cells and gray value appeared on day 21(P < 0.01), and the gray value on day 30 was lower than that on day 21 but still higher than that in the control group. Micro-CT revealed that the trabecula and the newly formed bone in the experimental group gradually thickened, and the number and separation of trabeculae increased with time. To conclude, both adult and growing rats display hyperplastic remodeling in the condyle with the presence of high expression of vascular endothelial growth factor under continuous mandibular advancement. However, the adaptive remodeling is earlier in the growing rats than in the adult rats.
引文
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[7]Lingaraj K,Poh CK,Wang W.Vascular endothelial growth factor(VEGF)is expressed during articular cartilage growth and re-expressed in osteoarthritis.AnnAcad Med Singapore.2010,39(5):399-403.
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[9]Corrado A,Neve A,Cantatore FP.Expression of vascularendothelial growth factor in normal,osteoarthritic andosteoporotic osteoblasts.Clin Exp Med.2013;13(1):81-84.
[10]Wang CJ,Huang KE,Sun YC,et al.VEGFmodulatesangiogenesis and osteogenesis in shockwave-promoted fracturehealing in rabbits.J Surg Res.2011;171(1):114-119.
[11]Peng H,Usas A,Olshanski A,et al.VEGF improves,whereassFlt1 inhibits,BMP2-induced bone formation and bone healingthrough modulation of angiogenesis.J Bone Miner Res.2005;20(11):2017-2027.
[12]Proff P,GedrangeT,FrankeR,etal.Histological and histomorphometric investigation of the condylar cartilage of juvenile pigs after anterior mandibular displacement.Ann Anat.2007;189(3):269-275.
[13]Rebaudi A,Koller B,Laib A,etal.Microcomputed tomographic analysis of the peri-implant bone.Int J Periodontics Restorative Dent.2004;24:316-325.
[2]傅民魁.口腔正畸学[M].北京:北京大学医学出版社,2014:119-120.
[3]詹静,谷志远.下颌前导后髁突骨形态学指标变化的动物实验[J].中华口腔医学杂志,2013,48(5):304-305.
[4]桑婷,伍军,黄臻,等.Herbst矫治器治疗年轻成人安氏Ⅱ类2分类错合牙的研究[J].华西口腔医学杂志,2012,30(1):49-53.
[5]Rabie AB,Xiong H,H?gg U.Forward mandibular positioning enhances condylar adaptation in adult rats.Eur J Orthod.2004;26(4):353-358.
[6]黄佳宁,陈秀锦.清洁级成年SD大鼠肝脏自发病变的组织病理学研究[J].动物医学进展,2012,33,(12):130-133.
[7]Lingaraj K,Poh CK,Wang W.Vascular endothelial growth factor(VEGF)is expressed during articular cartilage growth and re-expressed in osteoarthritis.AnnAcad Med Singapore.2010,39(5):399-403.
[8]Chim SM,Tickner J,Chow ST,et al.Angiogenic factors in bonelocal environment.Cytokine Growth Factor Rev.2013;24(3):297-310.
[9]Corrado A,Neve A,Cantatore FP.Expression of vascularendothelial growth factor in normal,osteoarthritic andosteoporotic osteoblasts.Clin Exp Med.2013;13(1):81-84.
[10]Wang CJ,Huang KE,Sun YC,et al.VEGFmodulatesangiogenesis and osteogenesis in shockwave-promoted fracturehealing in rabbits.J Surg Res.2011;171(1):114-119.
[11]Peng H,Usas A,Olshanski A,et al.VEGF improves,whereassFlt1 inhibits,BMP2-induced bone formation and bone healingthrough modulation of angiogenesis.J Bone Miner Res.2005;20(11):2017-2027.
[12]Proff P,GedrangeT,FrankeR,etal.Histological and histomorphometric investigation of the condylar cartilage of juvenile pigs after anterior mandibular displacement.Ann Anat.2007;189(3):269-275.
[13]Rebaudi A,Koller B,Laib A,etal.Microcomputed tomographic analysis of the peri-implant bone.Int J Periodontics Restorative Dent.2004;24:316-325.